Two changes to the IMP/Host Protocol to improve user/network communications (RFC0611)
Original Publication Date: 1974-Feb-14
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
1. A Reminder
Network Working Group D. Walden
RFC # 611 BBN-NET
NIC # 21354 February 14, 1974
TWO CHANGES T0 THE IMP/HOST PROTOCOL
TO IMPROVE USER/NETWORK COMMUNICATIONS*
1. A Reminder
When a host receives an IMP-Going Down message from its IMP (see
page 3-15 of BBN Report 1822, Specifications for the Interconnection of
a Host and an IMP), the Host should forward the information included in
the IMP-Going-Down message to its users from the network and its local
users of the network. Further, we suggest that the Host keep this
information around after the IMP has gone down, in order to tell local
users who are attempting to use the network.
In the next two sections of the RFC, we describe modifications to
the IMP/Host protocol which will allow the IMPs to distribute the same
sort of information about Hosts which are down.
2. Expansion of the Host-Going-Down Message
The type 2, Host-Going-Down, message described on page 3-1l of BBN
Report 1822 has not previously allowed for any provision by the Host for
additional information such as why, when, and for how long the Host is
going down. The following describes a modification to the Host-Going-
Down message which permits the Host to supply this additiona1
In a type 2, Host-Going-Down message, bits 17-28 give the time of
the Host's coming back up, bit-coded as follows:
bits 17-19: the day of the week the Host is coming back up. Monday is
day 0 and Sunday is day 6.
bits 20-24: the hour of the day, from hour 0 to hour 23, that the Host
is coming back up.
bits 25-28: the five minute interval, from 0 to 11, in the hour that
the Host is coning back up.
*Please file this RFC with your copy of BBN Report 1822 until that
report is updated.
All three of the above or to be specified in Universal time (i.e.,
G.M.T.). The Host may indicate that it will be coming back up more than
a week away by setting bits 17-28 all to ones. Setting all bits 17-27
to one and bit 28 to zero means it is unknown when the host is coming
Bits 29-32 of the Host-Going-Down message should be used by the Host
to specify the reason it is going down. These bits are coded as
0-4 Reserved for IMP use (see Section 3 below)
5 Scheduled P.M.
6 Scheduled Hardware Work
7 Scheduled Software Work
8 Emergency Restart
9 Power Outage
10 Software Breakpoint
11 Hardware Failure
l2-15 Currently Unused
It is assumed that as the time for the Host to go down approaches,
the Host itself will send warning messages to its network users. Just
before going down, the Host should send the Host-Going-Down message to
its IMP. The IMP will store this message and return it to the source
Host along with Destination (Host) Dead messages. The IMP will try to